The present invention relates to a rainbow forming device and more particularly to a device for forming an artificial rainbow for decorative purposes at any desired place for example in inner space of a building or a place where a fountain and/or trees have been placed.
Recently, many buildings have been designed with a lounge area that has a fountain and plants or trees. Particularly, in a hotel or the like such facilities are installed in a lobby or in a garden so as to create a pleasant atmosphere. However, such facilities are limited in their design and are usually similar to each other. Unusual designs are scarcely found which attract public attention.
In view of the foregoing, the applicant has previously proposed a rainbow-forming device which can create a rainbow artificially in a space such as in the lobby of a hotel or building in order to produce a certain atmosphere.
A rainbow-forming device previously proposed by the present applicant is such that sunlight or artificial white light made up of visible-spectral components is focused through a lens system and introduced into a light guide whereby the visible light (or the white light) is transmitted therethrough and emitted therefrom to go into a lens placed in opposition to a light-emitting end of the light guide, and the light is formed into a parallel light beam which enters into a set of prisms and is split into the colors of the spectrum and emitted therefrom to form a rainbow in a desired space. Practically, the device comprises a number of light guides aligned with each other for transmitting sunlight or artificial white light made up of visible-spectral components focused through a lens, a slender cylindrical lens is placed opposite to the aligned light-emitting ends of the light guides and a number of slender prisms are aligned with each other opposite the slender cylindrical lens. The parallel light beam, having passed through the cylindrical lens, enters into the prisms wherein it is split into a series of color components ranging from red (R) having long wavelengths to blue (B) with short wavelengths. An intermediate portion is made up of colors of the light components refracted in accordance with their wavelengths. Thus is formed a rainbow containing a series of colors arranged from upper red to lower blue in the order of their wavelengths.
Another example of a rainbow-forming device previously proposed by the present applicant comprises a single light guide and correspondingly a single round lens and a set of prisms arranged in a circle. It is also possible to use a single prism of a circular configuration instead of a set of prisms. Such a design of the rainbow-forming device makes it easier to arrange together a fiber optic cable, a lens and a prism and also to obtain an interesting rainbow of an almost circular form. However, the above-mentioned rainbow-forming device is rather large and is expensive since the light rays emitted from the light guide do not enter into the prism directly but through the round lens for obtaining a parallel light beam.